1. Field of the Invention
The present invention relates generally to facsimile apparatuses, and more particularly, to facsimile apparatuses having an image storing function of transmitting stored image data upon a request for data retrieval by a facsimile apparatus provided at a distant place.
2. Description of the Related Art
A facsimile apparatus of interest to the present invention is disclosed for example in Japanese Patent Laying-Open No. 2-72764, laid open Mar. 13, 1990. According to the official gazette of that document, a facsimile apparatus capable of storing received and read image data in an image memory sequentially transmits, as a transmitter, all the stored image data or designated image data, with a destination facsimile apparatus as a receiver, in accordance with the facsimile communication procedure upon a request for image data retrieval by the destination facsimile apparatus.
FIG. 5 shows the procedure of retrieving image data stored in an image storing unit at a request by a facsimile apparatus provided at a distant place. In the following description, a facsimile apparatus having a function of storing image is referred to as a transmission side and a facsimile apparatus at a distant place as a reception side.
First, the reception side calls up the transmission side (S21). The transmission side connects the line to establish a communication line between the transmission side and the reception side by the network. After the line connection by the transmission side, the reception side informs the transmission side of a code number necessary for data retrieval by using a DTMF (Dual Tone Multiple Frequency) signal (S22). The transmission side compares the code number received from the reception side with code numbers registered in its apparatus to prepare for receiving a retrieval request when the code numbers agree with each other. Subsequently to the code number, the reception side informs the transmission side of the retrieval request by using the DTMF signal (S23). The retrieval request usually includes either the information for retrieving all the image data stored in the image storing portion or the information for retrieving designated image data. At the retrieval request, the transmission side exchanges the signals with the reception side for transmitting image data in accordance with the facsimile communication procedure advised by CCITT (International Telegraph and Telephone Consultive Committee) (S24-S35).
More specifically, the transmission side transmits a CNG (Calling) signal (calling tone) indicative of the start of transmission (S24). The signal has a frequency of 1100 Hz and repetitionally turns on for 0.5 sec. and off for 3 sec. The reception side receives the CNG signal to send CED/DIS (Called/Digital Identification) signal (S25). The CED signal has a frequency of 2100 Hz and the duration of about 3 sec., which indicates that the reception side is functioning as a facsimile apparatus. The DIS signal is a binary code signal to be transmitted in a synchronization mode of 306 bps. The DIS signal includes information indicative of the reception capability of the reception side. On receiving the DIS signal, the transmission side sends a DCS (Digital Command Signal) as a binary code signal (S26) to inform the reception side of the transmission system matching the reception capability of the reception side. The transmission side transmits a TCF (Training Check) signal of "0" having a duration of 1.5 sec. at the same speed as the transmission speed (one of 2400, 4800, 7200 and 9600 bps) of the image data for the subsequent image data transmission (S27). When the reception side receives "0" of the TCF signal precisely, it is determined by the transmission side that the image data reception at the present speed involves reduced image data error, thereby sending a CFR (Communication to Receive) signal of a binary code signal (S28). The procedures at S27 and S28 are directed to verifying the quality of the network in use. When "0" can not be precisely received, that is, when the image data can not be received at that speed, the reception side sends an FTT (Failure to Train) signal, a binary code signal indicative of the necessity of communication at a lower transmission speed. Upon the reception of the CFR signal, the transmission side determines that the quality of the network in use is excellent to transmit the image data at the same speed as the TCF signal transmission speed (S29). The reception side prints the image data on recording paper to reproduce the image data. After finishing the transmission of the image data of one page, the transmission side sends an MPS (Multipage Signal) of a binary code signal when having another image data to be subsequently transmitted (S30). Upon the reception of the MPS signal, the reception side sends the binary code MCF signal as a response signal (S31) to proceed to a reception of the subsequent image data. After receiving the MCF signal, the transmission side transmits the subsequent image data (S32) and when finishing the transmission of the image data of one page, sees if there is any image data left to be subsequently transmitted. If there is, the transmission side sends the MPS signal (S30) and if there is no image data, the transmission side sends an EOP (End Of Procedure), a binary code signal indicative of the end of the transmission of the image data (S33). Upon receiving the EOP signal, the reception side sends an MCF (Message Confirmation) signal of a binary code signal as a response signal (S34). On receiving the MCF signal, the transmission side completes the transmission and sends a DCN (Disconnect) signal, binary code signal indicative of the release of the line (S35) to release the line. On receiving the DCN signal, also the reception side release the line to terminate the reception.
The above-described conventional facsimile apparatus, however, has a problem as follows.
In a case an image memory comprising a storage medium having a sequential arrangement and storing other data (for example, sound etc.) than image data (the storage format of the storage medium as shown in FIG. 6), for successively retrieving the image data from the storage medium by the request of retrieving all the image data stored in the image memory, the storage medium should be moved, after transmitting image data N11, to the position of image data N12 by skipping M11 which is a storage area for the data other than image data. This requires a time T for shifting. Image data N12 is transmittable if the shifting time T falls within a period from the end of the image data transmission indicated by S29 to the start of the subsequent image data transmission indicated by S32 in the facsimile communication procedure shown in FIG. 5 and if not, the image data N12 is non-transmittable. A time period from an end of an image data transmission to a start of an MPS transmission and a time period from an MCF reception to a start of a subsequent image data transmission are settled on CCITT standard. The shifting time T exceeding these time periods is regarded as error by a reception side in general. With such recording medium structure as described above, therefore, image data of all the pages can not be successively retrieved.
Such a problem as follows is presented by a request for retrieving designated image data out of image data stored in an image storing portion. While the designated image data is being retrieved, the image data is sequentially printed on recording paper at the reception side. Even if the operator at the reception side judges from the printed image data that related image data should be further retrieved, the facsimile communication procedure shown in FIG. 5 requires another series of operations for retrieving related image data to be performed after once releasing the line, which operations involve a waste of time and cost.